"Предложеные" is something like "perfect" form of time. Suggestion was complete some time ago (including moment ago!).
"Предлагаемые" is something like "indefinite" form of time.
However there is no strong relation with simple/past/perfect tense (and so on) in english. In fact they can be used almost identically with a very little bit of shifting accent only. There is almost no difference in usage.
"Предлагаемые нами сейчас решения"
"Предложенные нами сейчас решения"
"Предлагаемые нами в прошлом году решения"
"Предложенные нами в прошлом году решения"
All of these is correct.

I do not claim that my opinion is absolutely true.If you've spotted any mistake in my English, please, correct it. I want to be aware of any mistakes to efficiently eliminate them before they become a habit.